Molecular genetics has advanced to the stage where polynucleotides can be designed using genetic engineering principles to perform one or more specified functions. However, in order to achieve satisfactory results, multiple design principles must often be considered simultaneously. One example is that for convenient manipulation the presence or absence of specific restriction sites may be required. Another example is that for protein expression, the protein-encoding region of the polynucleotide should favor codons used most abundantly by the desired expression host. Another example is that for expression of a protein fused to a peptide tag, the reading frame between the protein and the tag must be maintained. Another example is that for expression of a protein, it is often desirable to minimize RNA secondary structures within the translation initiation region. Another example is that it is often desirable to alter the order of sequence elements within a polynucleotide construct. Thus, there is a need in the art for systems and methods that can aid in and simplify the process of designing a target nucleic acid sequence